The present invention relates to the field of laser communication devices.
The concept of laser communications is fairly mature. It is known to modulate laser beams with various types of data in order to transmit the data over substantial distances. U.S. Pat. No. 4,959,827 to Grotzinger et al. teaches voice modulation of a laser beam for secure voice communication, while U.S. Pat. No. 4,823,401 to Gammarino teaches modulation of a laser beam with binary data to be transmitted to a distant receiver for recovery of the data.
It is deemed desirable to provide devices for secure voice communication over one or two kilometers by modulation of a laser beam. The devices should be compact, light weight and portable in order to minimize adverse impact on the effectiveness of military ground combatants. It is also desirable to provide civilian police with a capability to operate in a dangerous night time mission such as attempting to arrest an armed criminal. Since police departments have limited budgets, cost is an important factor.
It is also deemed desirable to be able to give the police or military combatants the ability to see in the dark in order to determine the location and behavior of an armed person who may be occupying the darkened scene. Since cost is an important factor, what is really needed is the ability to provide secure voice communication along with the ability to see in the dark through the use of essentially the same piece of equipment which is not costly.